It is well known that aqueous fluids, in particular water, can be used as entraining agents in order, inter alia, to achieve a reduction in residual monomer contents when polymers are processed. This method can also achieve a reduction in the emission of volatile organic substances that may emit odors; this is a necessity when recycled polymers are processed.
In order to achieve maximum efficiency in introducing water into a polymer which is to be treated, porous particles charged with water can be incorporated into the polymer melt during the thermoplastic processing of the polymer. Water is driven off during the extrusion process and acts as entraining agent for volatile substances, and these are removed with the water vapor.
The porous particles used here are preferably made of hydrophobic polymers, for example polyethylenes or polypropylenes. A feature of these, inter alia, is high chemical stability and high mechanical and thermal stability. These polymers are therefore also suitable for the production of porous particles which can be charged with aqueous fluids and passed onward for further use.
WO 2005/003215 discloses porous, at least to some extent open-pored, particles respectively corresponding reservoirs charged with aqueous fluids. However a disadvantage of particles or reservoirs of this type is that the particles have to be equipped with a relatively large amount of surfactant before they are charged with water. That is the only way of achieving a charging level of more than 50% using an aqueous fluid. However, the charging of particles with relatively large amounts of surfactants is problematic because these surfactants can exert a not inconsiderable effect on the desired use of the charge. When the charged reservoirs are used to deliver entraining agent, one possibility inter alia is that the surfactants form degradation products which firstly consume entraining agent, i.e. water, and secondly also can themselves be odor-generating substances.
It was therefore an object of the present invention to provide a reservoir which has a high level of charge of aqueous fluids, whereby the entire charge of the reservoir is available without impairment, i.e. in essence entirely, for the desired use.